If all that comes to mind when you think of a winter cruise is a queasy stomach, you may find solace in ginger. In folklore, ginger has a formidable reputation as an anti-nausea agent. According to Albert Leung, an independent consultant in plant pharmacology, ginger has been used for centuries in the Orient to combat seasickness. "It's quite common today," he says, "to see people in boats around Hong Kong munching on preserved ginger." Dr. James Duke, an authority on medicinal plants at the U.S. Department of Agriculture, says: "Legend has it that commercial fishermen at sea would chew on a slug of ginger root to ward off decidedly unprofitable bouts of seasickness." Is there any truth to it? Surprisingly, yes. The evidence is good and getting better. In 1982, two researchers at Brigham Young University and Mount Union College in Ohio demonstrated that powdered ginger root was better than Dramamine -- a common anti-motion-sickness drug -- at suppressing motion-induced nausea. In their test, they put people highly prone to seasickness in a whirling tilted chair, a motion that brings on stomach-turning sensations. Twenty minutes prior to that, they gave the subjects either a placebo (with no pharmacological value), Dramamine, or powdered ginger root -- the same stuff you get at the supermarket, except it was in a capsule. The dose of ginger was about a gram -- or half a teaspoonful. None of the volunteers who took Dramamine or a placebo lasted in the twirling chair for six minutes without vomiting or becoming nauseated. Half of those who took the ginger did. One of the investigators, psychologist Daniel Mowrey, then at Brigham Young, thinks the ginger somehow "interrupts the feedback between the stomach and the nausea center of the brain." A later double-blind study in 1986 at Odense University in Denmark, found that ginger blocked vertigo in all of eight subjects, apparently by affecting the inner ear, which is also implicated in motion sickness. Such laboratory studies are well and good, but the real truth is revealed only on the high seas. So that's where the Danes went next -- to 80 green naval cadets "unaccustomed sailing in heavy seas." In a recently published report of the double-blind study, the Danish researchers recount how one day out of port as the ship hit high seas, they gave 1 gram of ginger root to one group of the rookie sailors and a placebo to another group. Then they examined them for symptoms of seasickness every hour for four hours. Sure enough, ginger root reduced the severity of seasickness by suppressing vomiting, cold sweating, nausea and vertigo. The most pronounced effect was control of vomiting -- dampening it by 72 percent. Over all, they pronounced ginger 38 percent protective against the symptoms of seasickness. The Danish scientists note that the pharmacological component in ginger that combats motion sickness is totally unknown. However, they say it takes effect within 25 minutes and lasts for at least four hours. Duke recommends putting half a teaspoon of powdered ginger in tea or another beverage. If you use fresh grated ginger root, you need twice that much, he says. More convenient are capsules of ginger often sold in health food stores. According to Mowrey, two or three capsules, each containing 500 milligrams of powdered ginger, should do the trick -- if taken about half an hour before encountering the motion. He cautions against swallowing the dry ginger plain, noting it could burn the esophagus. Duke figures that a 12-ounce can of ginger ale or ginger beer may also contain enough ginger to prevent motion sickness in some people more effectively than 50 to 100 milligrams of Dramamine. Curbing motion sickness is not ginger's only pharmacological asset. In animal tests, ginger lowers blood cholesterol; in test tubes it is an antibiotic, very effective against salmonella, the bacteria that frequently contaminate eggs and chickens. (Could that account for the Chinese wisdom behind ginger chicken?) Ginger is a strong antioxidant, says Duke, perhaps giving it some anti-cancer properties. But in certain medical circles ginger is best recognized as a blood thinner. A few years ago, Dr. Charles R. Dorso, then at Cornell University Medical College, noticed that his blood did not coagulate as usual. He traced the effect to eating large quantities of ginger marmalade that was 15 percent ginger. In tests, he found that ginger behaved like an anticoagulant: It reduced the tendency of blood platelets to stick together. He attributed the effect to gingerol, a ginger compound chemically structured like aspirin, a well-known anti-clotting agent. Several studies confirm ginger's potent ability to manipulate prostaglandins, body chemicals that help control blood cell stickiness and clumping. A scientist even suggested recently in a medical journal that ginger replace certain drugs that act on prostaglandins, because of their dangerous side effects. Ginger is designated by the government as GRAS, which stands for "generally recognized as safe," and has few documented side effects. In combatting motion sickness, it reportedly does not cause drowiness, as some drugs do. Eating Right appears on alternate Tuesdays.